af9013: Don't accept invalid bandwidth

commit d7b76c91f471413de9ded837bddeca2164786571 upstream.

If userspace sends an invalid bandwidth, it should either return
EINVAL or switch to auto mode.

This driver will go past an array and program the hardware on a
wrong way if this happens.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>